In an attempt to mitigate carbon dioxide emissions, new technologies are being proposed that can aid in greenhouse gas sequestration. One such technology involves trapping carbon dioxide in hydrate form. To optimize this process, it is of interest to investigate how the hydrate system behaves in the presence of promoting agents. In this work, the effect of asproduced and amine-functionalized multi-wall carbon nanotubes (MWNTs) on carbon dioxide dissolution and hydrate growth rates was studied. For either type of the MWNTs, the effect on saturation values and dissolution rates was negligible. Under lower concentrations, it was found that both forms of MWNTs enhanced growth, with the functionalized MWNTs performing slightly better. Under higher concentrations, both forms of MWNTs decreased growth rates, because the initial nucleation event was more pronounced and led to heat-and mass-transfer limitations.
Amine-functionalized multi-walled carbon nanotubes (MWCNTs) dispersed in water are investigated as CO 2 absorbents. MWCNTs grown by chemical vapor deposition on stainless steel meshes form open forests that can be coated via a RF capacitively coupled glow discharge. When treating the MWCNTs in an atmosphere containing either pure ammonia or mixtures of ammonia and ethylene for 5 min, grafting of nitrogen functional groups or deposition of a nitrogen-rich plasma polymer layer occurs. In particular, for a 1:1 mixture, a 10 nm thick plasma polymer layer coats the MWCNTs. This layer contains about 19 N at%, and 12% of these nitrogen atoms are nucleophilic sites (such as amines) that may react with CO 2 . These functional groups not only enhance the absorption of CO 2 , but also increase the hydrophilic character of the MWCNTs, allowing them to stay suspended in water for at least three months at room temperature. The CO 2 absorption capacity of this nanofluid is 36% higher than that of water, with a MWCNT concentration of about 40 mg L À1 .
Interaction of 7-mercapto-4-methylcoumarin with the surface of core-shell CdSe-ZnS quantum dots leads to characteristic absorption and emission bands that are excellent reporters for thiol interactions at the nanoparticle surface.
The stability in water of multi‐walled carbon nanotubes (MWCNTs) coated with N‐ or O‐rich plasma polymers (PPs) is investigated at different pH values. MWCNTs are coated with PPs by plasma enhanced chemical vapor deposition of ethylene and ammonia or ethylene and carbon dioxide. MWCNTs coated with N‐rich PP in water at pH 12 exist as agglomerates that readily sediment, whereas, the agglomerate size decreases and suspension stability increases as the pH changes from 10 to 2. The reverse effect is observed for MWCNTs coated with O‐rich PP which form agglomerates at pH 2, but are stable from pH 4–12. By switching the pH of suspensions containing either one of these coated MWCNTs, it is possible to cycle through destabilization and dispersion steps.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.